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Subject: Re: [boost] Request for interest in the new Synchro library
From: James Mansion (james_at_[hidden])
Date: 2009-02-19 15:30:10

Dmitry Goncharov wrote:
> I need to block a thread until either a timeout expires or some other
> thread wakes this one up. This is really what
> condition_variable::timed_wait() is for, right?
> Why can't condition_variable::timed_wait() be used? It can. It has a
> drawback, though.
> After the condvar was signaled it has to lock a mutex. This means
> there is an unbound timeout between the time condvar was signaled and
> the time condition_variable::timed_wait() returns.
Why is that any more unbounded than any other code that has to happen
inside the gubbins of binary_semaphore?

After all, something, somewhere, has to wake up and then test to see
whether it was timed out or woken up. Which implies a state variable,
which implies a mutex to protect it, which implies you're not winning
how you think you are.
> A binary_semaphore::timed_wait() can be used for the same purpose. The
> advantage is it doesn't have to lock a mutex.
I think the advantage is that its actually a portable abstraction, in a
way that a condition_variable isn't.


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